It is known, in fluorescence microscopy and in biochip applications, for spatially resolved, photometric measurement of fluorescent substances, to apply these substances on a transparent carrier plate, the so-called specimen slide. The fluorescent substances are then excited using suitable radiation, and fluorescent radiation they emit is detected in a spatially resolved manner. In the interest of good precision of measurement, falsifications of the fluorescent radiation intensity should, in this case, be kept to a minimum.
Therefore, confocal microscopes are presently used for high-precision measurements, said confocal microscopes having such a low depth of focus that they receive fluorescent radiation only from the fluorescent substance layer to be analyzed. This effectively blocks out radiation within the fluorescent wave-length range originating from other regions. Thus, it is ensured that fluorescent radiation is picked up only from an area to be analyzed. However, this advantage is obtained at the cost of a corresponding complexity of microscope equipment, since the focusing ability required for confocal imaging in the microscope is usually achievable only by means of a laser. Moreover, this strongly restricts the choice of the light source.
Another approach provides for taking a plurality of spatially resolved pictures in different ranges of depth of the objective and for subsequent mathematical processing thereof. However, this approach requires calculations of considerable complexity, so that it takes longer to take a picture. Further, the sensitivity of detection may be reduced.
Moreover, this known method is only conditionally suitable for handling processes in a time-resolved manner, because taking a plurality of pictures and effecting the required subsequent mathematical processing takes a certain time.
If the complexity of a confocal measurement microscope or the above-described mathematical correction is dispensed with, a falsification of the measurement result has to be accepted or the sensitivity of measurement needs to be lowered.
On Nov. 20, 2001, the Electron Microscopy Sciences Catalog depicted a specimen slide under order no. 71876-0, said specimen slide having its bottom surface roughened by sand blasting. According to the explanation in the catalog, such roughening serves to ensure better writeability of the bottom surface of the specimen slide.